Backside coating for transparent substrate

Abstract

Embodiments described herein relate to semiconductor processing. More specifically, embodiments described herein relate to processing of transparent substrates. A film is deposited on a backside of the transparent substrate. A thickness of the film is determined such that the film reflects particular wavelengths of light and substantially prevents bowing of the substrate. The film provides constructive interference to the particular wavelengths of light.

What is claimed is: 
     
         1 . A method of depositing a film, comprising:
 obtaining a wavelength of light emitted from a sensor;   identifying a refractive index of a material;   determining a target thickness of the material by dividing the wavelength of the light emitted from the sensor by two times the refractive index of the material; and   depositing the material on a substrate to form a film having the target thickness.   
     
     
         2 . The method of  claim 1 , wherein the wavelength of the light emitted from the sensor is between about 500 nm and about 700 nm. 
     
     
         3 . The method of  claim 2 , wherein the wavelength of the light emitted from the sensor is about 650 nm. 
     
     
         4 . The method of  claim 1 , further comprising:
 depositing one or more layers on a side of the substrate opposite the film.   
     
     
         5 . The method of  claim 1 , wherein the target thickness is between about 300 nm and about 450 nm. 
     
     
         6 . The method of  claim 1 , wherein the film causes constructive interference of the light emitted from the sensor. 
     
     
         7 . The method of  claim 1 , further comprising:
 performing a selective etch to remove the film from the substrate.   
     
     
         8 . The method of  claim 1 , wherein a refractive index is a ratio of a speed of light traveling through the material to a speed of light traveling through a vacuum. 
     
     
         9 . A method of depositing a film, comprising:
 obtaining a wavelength of light emitted from a sensor;   identifying a refractive index of a silicon containing material;   determining a target thickness of the material by dividing the wavelength of the light emitted from the sensor by two times the refractive index of the material; and   depositing the material on a substrate to form a film having the target thickness.   
     
     
         10 . The method of  claim 9 , wherein the silicon containing material comprises silicon nitride. 
     
     
         11 . The method of  claim 9 , wherein the wavelength of the light emitted from the sensor is between about 500 nm and about 700 nm. 
     
     
         12 . The method of  claim 9 , wherein the wavelength of the light emitted from the sensor is about 650 nm. 
     
     
         13 . The method of  claim 9 , further comprising:
 depositing one or more layers on a side of the substrate opposite the film.   
     
     
         14 . The method of  claim 9 , wherein the target thickness is between about 300 nm and about 450 nm. 
     
     
         15 . The method of  claim 9 , further comprising:
 performing a selective etch to remove the film from the substrate.   
     
     
         16 . The method of  claim 9 , wherein the film increases at least one of a reflectivity and an opacity of the substrate. 
     
     
         17 . An apparatus, comprising:
 a transparent substrate having a first side and a second side opposite the first side; and   a film deposited on the second side of the substrate, the film having a thickness equivalent to a wavelength of light emitted from a sensor divided by two times a refractive index of a material of the film.   
     
     
         18 . The apparatus of  claim 17 , further comprising:
 one or more layers deposited on the first side of the substrate.   
     
     
         19 . The apparatus of  claim 17 , wherein the film is a reflective film which reflects light of the wavelength of the sensor. 
     
     
         20 . The apparatus of  claim 17 , wherein the film comprises silicon nitride.